1. Field of the Invention
This invention relates to cardiac pacers, and more particularly, to cardiac pacers employing digital circuitry means for controlling the pacer operation.
2. Description of the Prior Art
Digital cardiac pacers have been described, most of which are intended for implantation into the body of the patient.
In so far as is known to applicant, none of the digital pacers heretofore advanced present means for providing an upper limit upon the stimulation pulse production rate which may occur as a result in the change in value of a critical pacer timing component. Additionally, especially in pacers which are primarily intended for external use, battery lifetime considerations are for the most part not considered, or at least are not of primary importance; consequently, most heart pacers of the prior art require frequent battery replacement.
What is needed is a pacer which can be employed externally to the patient, which can selectively provide an indication of its proper operation, which provides a circuit to prevent runaway of the pacer due to component drifts, and which is efficient in its power consumption requirements.